| Cognitive control is necessary to integrate cognitive processes with rules or goals when we perform a complex or irregular task. Diverse areas of prefrontal cortex (PFC) have been associated with cognitive control. The purpose of this study was to reveal neural mechanisms underlying cognitive control in conflict regulation and set switching. Using functional magnetic resonance imaging (fMRI), blood-oxygenation-level-dependent (BOLD) signals were acquired to measure brain activation during cognitive set switching, conflict regulation and the preparation for them. Behavioral results demonstrated that the conflict effect, the switch cost and the preparation effect were significant. fMRI results showed that medial/lateral frontopolar cortex (FPC) and pre-supplementary motor cortex (pre-SMA) were sensitive only to switching demands, while rostral regions of dorsal anterior cingulate cortex (dACC) were selectively activated by conflict regulation. By contrast, dorsolateral PFC (DLPFC) and caudal dACC were commonly activated by both set switching and conflict regulation. The rostral part of dorsal premotor cortex (pre-PMd) was activated by selection of the stimulus representation as well as the both cognitive control demands. These findings suggest that different regions of PFC play different roles in cognitive control according to the processing level. Specifically, lateral FPC, DLPFC and pre-PMd might be associated with higher-level cognitive control, response control, and stimulus control, respectively. In addition, each region of medial PFC including medial FPC, rostral and caudal dACC and pre-SMA is functionally dissociated, suggesting that each region is involved in selection of the cognitive set, the response set and the stimulus set and the reconfiguration processing during set switching, respectively. In conclusion, this study suggests that diverse PFC regions are functionally organized according to cognitive control demands. |
